Java Program to Calculate Maximum Annuity for a Given Investment
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import java.awt.*;2
import java.awt.event.*;3
import javax.swing.*;4
import java.text.*;5
/*6
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*/9
public class MaxWD extends JApplet10
implements ActionListener {11
JTextField maxWDText, orgPText, periodText,12
rateText, numWDText;13
JButton doIt;14
double principal;15
double rateOfRet;16
double numYears;17
int numPerYear;18
NumberFormat nf;19
public void init() {20
try {21
SwingUtilities.invokeAndWait(new Runnable () {22
public void run() {23
makeGUI();24
}25
});26
} catch(Exception exc) {27
System.out.println("Can't create because of "+ exc);28
}29
}30
private void makeGUI() {31
GridBagLayout gbag = new GridBagLayout();32
GridBagConstraints gbc = new GridBagConstraints();33
setLayout(gbag);34
JLabel heading = new35
JLabel("Maximum Regular Withdrawals");36
JLabel orgPLab = new JLabel("Original Principal ");37
JLabel periodLab = new JLabel("Years ");38
JLabel rateLab = new JLabel("Rate of Return ");39
JLabel numWDLab =40
new JLabel("Number of Withdrawals per Year ");41
JLabel maxWDLab = new JLabel("Maximum Withdrawal ");42
maxWDText = new JTextField(10);43
periodText = new JTextField(10);44
orgPText = new JTextField(10);45
rateText = new JTextField(10);46
numWDText = new JTextField(10);47
maxWDText.setEditable(false);48
doIt = new JButton("Compute");49
gbc.weighty = 1.0;50
gbc.gridwidth = GridBagConstraints.REMAINDER;51
gbc.anchor = GridBagConstraints.NORTH;52
gbag.setConstraints(heading, gbc);53
gbc.anchor = GridBagConstraints.EAST;54
gbc.gridwidth = GridBagConstraints.RELATIVE;55
gbag.setConstraints(orgPLab, gbc);56
gbc.gridwidth = GridBagConstraints.REMAINDER;57
gbag.setConstraints(orgPText, gbc);58
gbc.gridwidth = GridBagConstraints.RELATIVE;59
gbag.setConstraints(periodLab, gbc);60
gbc.gridwidth = GridBagConstraints.REMAINDER;61
gbag.setConstraints(periodText, gbc);62
gbc.gridwidth = GridBagConstraints.RELATIVE;63
gbag.setConstraints(rateLab, gbc);64
gbc.gridwidth = GridBagConstraints.REMAINDER;65
gbag.setConstraints(rateText, gbc);66
gbc.gridwidth = GridBagConstraints.RELATIVE;67
gbag.setConstraints(numWDLab, gbc);68
gbc.gridwidth = GridBagConstraints.REMAINDER;69
gbag.setConstraints(numWDText, gbc);70
gbc.gridwidth = GridBagConstraints.RELATIVE;71
gbag.setConstraints(maxWDLab, gbc);72
gbc.gridwidth = GridBagConstraints.REMAINDER;73
gbag.setConstraints(maxWDText, gbc);74
gbc.anchor = GridBagConstraints.CENTER;75
gbag.setConstraints(doIt, gbc);76
add(heading);77
add(orgPLab);78
add(orgPText);79
add(periodLab);80
add(periodText);81
add(rateLab);82
add(rateText);83
add(numWDLab);84
add(numWDText);85
add(maxWDLab);86
add(maxWDText);87
add(doIt);88
orgPText.addActionListener(this);89
periodText.addActionListener(this);90
rateText.addActionListener(this);91
numWDText.addActionListener(this);92
doIt.addActionListener(this);93
nf = NumberFormat.getInstance();94
nf.setMinimumFractionDigits(2);95
nf.setMaximumFractionDigits(2);96
}97
public void actionPerformed(ActionEvent ae) {98
double result = 0.0;99
String orgPStr = orgPText.getText();100
String periodStr = periodText.getText();101
String rateStr = rateText.getText();102
String numWDStr = numWDText.getText();103
try {104
if(orgPStr.length() != 0 &&105
periodStr.length() != 0 &&106
rateStr.length() != 0 &&107
numWDStr.length() != 0) {108
principal = Double.parseDouble(orgPStr);109
numYears = Double.parseDouble(periodStr);110
rateOfRet = Double.parseDouble(rateStr) / 100;111
numPerYear = Integer.parseInt(numWDStr);112
result = compute();113
maxWDText.setText(nf.format(result));114
}115
showStatus("");116
} catch (NumberFormatException exc) {117
showStatus("Invalid Data");118
maxWDText.setText("");119
}120
}121
double compute() {122
double b, e;123
double t1, t2;124
t1 = rateOfRet / numPerYear;125
b = (1 + t1);126
e = numPerYear * numYears;127
t2 = Math.pow(b, e) - 1;128
return principal * (t1/t2 + t1);129
}130
}